Going off of what I leaned, concussions are caused by the brain bouncing around the skull. If my memory serves, Crawford's head didn't twist on the horizontal axis much nor did it snap back that violently (certainly not as hard as the head-acceleration Hossa had when Torres blindsided him)--nor did it look like his head bounced off the ice like Parros'.
While I certainly would have quiet-roomed him for the rest of the period, I think his play since proved it wasn't too serious--after all, he did carry the carcasses of all 6 d-men for the remainder of the game.
Bobby Hull has the fastest shot recorded, at 118.3mph. He's been on record saying his brother Dennis, was even harder. So, yeah, they could have killed someone back then but I think most of that was in the pre-curved stick era so the shots tended low and I believe when they started at the NHL level it was still illegal for a goalie to drop down.